JP3092835B2 - Signal playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a DAT (Digital Audi)
The present invention relates to a signal reproducing apparatus for reproducing a signal such as an audio signal recorded on a recording medium such as a tape, and more particularly, to a signal reproducing apparatus capable of instantaneously and accurately starting reproduction of a signal from its rise. Further, the present invention relates to a signal rising position detecting unit capable of detecting the rising positions of various signals more accurately.

[0002]

2. Description of the Related Art Conventionally, for example, when an audio signal is recorded on a DAT, an identification signal called a start ID is recorded at a start position of the audio signal. Then, when reproducing the audio signal, the reproduction of the signal is started from the position where the start ID is detected. However, in many cases, the position on the DAT where the start ID is recorded is different from the actual rising position of the audio signal. Therefore, in the DAT reproducing apparatus, the recording position of the start ID can be changed by manual operation while listening to music or the like obtained by actually reproducing the audio signal.

[0003] Also, on a CD (Compact Disk),
Although the start ID is recorded at the start position of the audio signal, the recording position of the start ID does not exactly match the actual rising position of the audio signal. Conventional C
In the playback device D, in a pause state, as shown in FIG. 14, the track Tr ₀ on which the start ID is recorded is repeatedly played back. During the repeat reproduction, a position on the CD 1 where the level of the reproduction signal greatly changes is detected, and the position is stored. Then, when a reproduction start operation is performed, the signal is reproduced from the stored position regardless of the start ID.

[0004]

The correction of the signal reproducing position as performed in the above-described CD reproducing apparatus is performed by DA.
It is conceivable that the present invention is applied to the T reproducing apparatus.

[0005] However, since the DAT is a tape-shaped recording medium, it takes a long time for the DAT repeat operation to repeat a predetermined range including the position where the start ID is recorded. Further, since the rising position of the detected signal is specified on the DAT (recording medium), it is difficult to instantaneously reproduce the audio signal from the detected position at the time of the start operation.

[0006] The DAT reproducing apparatus employs a technique in which an audio signal within a predetermined range including a start ID on the DAT is stored in a memory in advance, and an audio signal is read from a position corresponding to the start ID on the memory at the time of a start operation. ing. If such a technique is used, it is possible to instantaneously reproduce an audio signal from the above-described detected rising position at the time of a start operation.

However, as described above, the recording medium (DA
T) It is necessary to repeat the reproduction in order to detect the rising position of the signal above, and furthermore, after detecting the rising position, a signal in a predetermined range including the rising position must be reproduced again and stored in the memory. No. Therefore, it takes a lot of time until a reproduction signal can be output.

An audio signal to be recorded on a recording medium such as a DAT can include various background signals (noise, etc.). That is, the signal level in the silent state may be different from the background signal corresponding to the recording state. Therefore, as in the related art, when the rising position of a signal is detected using a single reference level, various signals recorded in different states of the background signal, or even when the background signal is in a silent state, the signal is gradual. The rising position of a rising signal or a signal rising to a high level while a low-level signal continues cannot be accurately detected.

Therefore, the present invention relates to a method for controlling the recording medium, even if the recording medium is D
Even those tape-shaped, such as AT, signal regeneration and purpose thereof is to provide a signal reproducing apparatus which allow instantly from the rising.

[0010]

Means for Solving the Problems] To achieve the above Symbol purpose, the present invention shows an audio signal recorded on a recording medium (13) the starting position on the recording medium of the audio signal (13) In a signal reproducing apparatus for reproducing using start position information (ID), a reproduction signal output means (16) for reading out an audio signal from a recording medium (13) and outputting a reproduction signal, and a memory means for storing the reproduction signal ( 2
2) and the reproduction signal output from the reproduction signal output means (16) in a predetermined range on the recording medium (13) including the position specified by the start position information (ID) is stored in the memory means (22). Control means (18, 19) for performing
The memory means (2) is controlled by the control means (18, 19).
2) a rising position detecting means (17, 18) for detecting a position in the memory means (22) of a rising edge of the reproduction signal; and the rising position detecting means (1).
Memory means (22) from the position detected in (7, 18)
Memory control means (1) for starting reading of a reproduction signal in the memory
8, 19).

[0011]

[0012]

[0013]

The reproduced signals output from the reproduced signal output means (16) are sequentially stored in the memory means (22). The reproduced signal is supplied to rising position detecting means (17, 18), and the position of the rising of the reproduced signal in the memory (22) is detected. Then, the memory control means (18,
19) starts reading of the reproduction signal in the memory means (22) from the detection position.

[0014]

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration of a signal reproducing apparatus according to an embodiment of the present invention.

The signal reproducing apparatus shown in FIG.
This is a magnetic recording / reproducing device 11 called T (Digital Audio Tape Recoder). The magnetic recording / reproducing signal 11 has a tape drive mechanism 12 for moving a magnetic tape 13 (DAT) in a fixed direction. In the tape drive mechanism 12, the magnetic tape 13 is guided by a guide shaft 14 so as to run along the surface of the rotary head 15. The rotary head 15 is connected to a signal processing circuit 16 that performs processing such as RF modulation and error correction. The signal processing circuit 16 outputs a reproduction signal based on a read signal from the rotating head 15 and a reproduction signal output circuit 16a which processes a start code and time information recorded on the magnetic tape 13 together with the audio signal. And a serve code processing circuit 16b. The reproduction signal output circuit 16a outputs a digital reproduction signal, and the digital reproduction signal is supplied to a level determination circuit 17 and a memory 22 composed of a ring buffer. The subcode processing circuit 16b is connected to the microcomputer 18.

The memory control circuit 19 controls writing and reading of the memory 22 based on a command from the microcomputer 18. The reproduction signal read from the memory 22 is supplied to the output unit 21 via the D / A converter 20. An operation unit 23 having a keyboard is connected to the microcomputer 18. The microcomputer 18 inputs the subcode from the subcode processing circuit 16b, the judgment result obtained by the level judgment circuit 17, and the input information from the operation unit 23, and based on these information, the tape drive mechanism 12 and the memory control Circuit 19
To control the whole system.

The level determination circuit 17 is configured, for example, as shown in FIG.

In FIG. 2, a level judging circuit 17 comprises a serial / parallel converter 24 and a bit judging circuit 25.
And a latch circuit 26. The serial / parallel converter 24 converts the digital reproduction signal from the reproduction signal output circuit 16a into parallel data, and supplies the data to the bit determination circuit 25. Bit determination circuit 25
Compares the reference level corresponding to the level setting signal supplied from the microcomputer 18 with the level of the reproduction signal supplied through the serial / parallel converter 24, and determines whether the level of the reproduction signal exceeds the reference level. Has been determined. The microcomputer 18 selects one of the level setting signals corresponding to the four types of reference levels and supplies it to the bit determination circuit 25. The latch circuit 26 latches the result of the determination by the bit determination circuit 25. The result of the determination by the bit determination circuit 25 is, for example,
Bit "1" when the level of the reproduction signal is higher than the reference level
When the level of the reproduction signal is lower than the reference level, it is represented by bit "0". Microcomputer 1
Numeral 8 periodically monitors the determination result latched by the latch circuit 26, and switches the level setting signal based on the determination result. The microcomputer 18 detects the rising edge of the reproduction signal based on the change in the determination result latched by the latch circuit 26.

When the operator operates the skip button in the operation unit 23 in order to reproduce the music recorded on the magnetic tape 13 (DAT) from the beginning, the processing shown in FIG. 3 is performed.

The microcomputer 18 outputs a tape winding start signal to the tape drive mechanism 12 based on the operation of the skip button (ST1). With this signal, the tape drive mechanism 12 performs a fast-forward operation or a rewind operation, and the magnetic tape 13 is wound (ST).
2). While the winding of the magnetic tape 13 is being performed, the microcomputer 18 determines whether or not the start ID is read (ST3). When the start ID is read, the start I
A D detection signal is output. When it is determined that the start ID has been read based on the start ID detection signal,
The microcomputer 18 calculates 1-2 from the start ID.
Drive mechanism 1 so that the magnetic tape 13 is wound up to a second
2 is controlled (ST4).

Thereafter, the microcomputer 18 determines whether or not an automatic cue mode (AUTO CUE MODE) is set (ST5). This automatic cue mode can be set by operating the automatic cue switch of the operation unit 23. Here, when the automatic cue mode is set, signal reproduction from the magnetic tape 13 is started (ST6). At this time, a data write start signal is supplied from the microcomputer 18 to the memory control circuit 19 (ST7), and the memory control circuit 19 writes the reproduction signal output from the reproduction signal output circuit 16a into the memory 22. That is, 1 from the start ID on the magnetic tape 13
A reproduced signal sequentially read out from a position before the time of about 2 seconds (tape time) is stored in the memory 22 as shown in FIGS.
(Ring buffer). The reproduced signal from the reproduced signal output circuit 16a is supplied to the level determination circuit 17
Is also supplied. The level determination circuit 17 determines the level of the supplied reproduction signal, and based on the determination result,
The microcomputer 18 detects the rise of the reproduction signal (ST8). The process of detecting the rise in step ST8 will be described later. When the rise of the reproduction signal is detected, the address of the rise position on the memory 22 and the tape time are stored in a memory (not shown) in the microcomputer 18 (ST9). Thereafter, the writing of the reproduction signal to the memory 22 is stopped three seconds (tape time) from the rise of the reproduction signal (ST10).

When the writing of the reproduction signal to the memory 22 is stopped, the microcomputer 18
The tape drive mechanism 12 is controlled so that is rewinded for 2 seconds (tape time) (ST16). Then, the microcomputer 18 enters a standby state and waits for an operation input (ST17). At this time, the reproduction position on the magnetic tape 13 is held at the standby point shown in FIG.

In the above processing, the memory control circuit 19 supplies the microcomputer 18 with the address of the memory 22 for always storing the reproduction signal and the tape time information indicating the position of the signal on the magnetic tape 13. I have.

When the stop button of the operation unit 23 is operated when the microcomputer 18 is in the standby state as described above (ST18), all the operation states are reset and the processing is terminated. On the other hand, when the start button of the operation unit 23 is operated (ST19),
The standby state is released. Then, reading of the memory 22 is started from the address corresponding to the rising position (correction start point) of the reproduction signal stored in the internal memory of the microcomputer 18 (ST20).
Then, the operation of the tape drive mechanism 12 is started based on a command from the microcomputer 18, and signal reproduction is started from the standby point (ST21). The reproduction signal read from the memory 22 is converted into an analog signal by the D / A converter 20 and is sequentially supplied to the output unit 21. Also, after signal playback is started from the standby point,
The microcomputer 18 refers to the subcode information read from the magnetic tape 13 together with the signal reproduction,
The tape time information is stored in the memory 2 in step ST10.
Then, it is determined whether or not it matches the tape time information (stored in the internal memory) at the time of stopping the writing to ST2 (ST22). Here, when the read tape time information matches the tape time information stored in the internal memory, the memory control circuit 19 resumes the operation of writing the reproduction signal output from the reproduction signal output circuit 16a into the memory 22. Thereafter, the memory control circuit 19 operates as the reproduction signal output circuit 1
The reproduction signal output from 6a is written into the memory 22, and the reproduction signal stored in the memory 22 is sequentially read.
The position where the writing of the reproduction signal to the memory 22 is started is shown as an additional writing point in FIG. On the other hand, when the microcomputer 18 determines that the automatic cue mode is not set in step ST5, the process proceeds to step ST11. In step ST11, signal reproduction from the magnetic tape 13 is started. At this time, a data write start signal is supplied from the microcomputer 18 to the memory control circuit 19 (ST12), and the reproduced signal output from the reproduced signal output circuit 16a is written into the memory 22. That is, also in this case, similarly to the automatic cue mode, reproduced signals sequentially read from a position one to two seconds (tape time) before the start ID on the magnetic tape 13 are stored in the memory 22 as shown in FIG. You. Thus, the reproduced signal is stored in the memory 2
When the microcomputer 18 detects the start ID while the signal is stored in the memory 2 (ST13), the signal is continuously reproduced for 3 seconds (tape time) (ST14).
The reproduced signal is written into the memory 22. And start ID
When 3 seconds (tape time) elapses after detecting
Writing to the memory 22 is stopped.

Thereafter, the processes in steps ST18 to ST23 are performed in the same manner as in the automatic queue mode. In the process of this processing, in step ST20, the memory 2 is read from the address corresponding to the position (start point) of the start ID.
2 is started.

According to the above processing, in the automatic cue mode, the rising edge of the reproduction signal is detected and its memory 22
The upper position (address) is stored in the internal memory of the microcomputer 18. Then, when the start button is operated thereafter, reading of the reproduction signal is started from the address on the memory 22 corresponding to the rising position of the reproduction signal. If the mode is not the automatic cue mode, reading of the reproduction signal is started from the address on the memory 22 corresponding to the position of the start ID. Therefore, in the automatic cue mode, even if the position of the start ID is deviated from the actual rising position of the reproduced signal, the reproduced signal is accurately output from the rising point.

The process of detecting the rising edge of the reproduced signal in step ST8 is executed according to the flowcharts shown in FIGS. 6, 7, and 8.

The microcomputer 18 outputs one of the following four types of level setting signals. The first level setting signal is a first reference level (for example, -70 dB)
, The second level setting signal corresponds to a second reference level (eg, −65 dB), the third level setting signal corresponds to a third reference level (eg, −60 dB), and The fourth level setting signal corresponds to the fourth reference level (-55 dB). That is, the first reference level is the lowest level, the fourth reference level is the highest level, and the second reference level is lower than the third reference level.

Immediately after the start of signal reproduction, the microcomputer 18 sends the first level setting signal to the level determination circuit 17.
And the level determination circuit 17 determines whether or not the level of the reproduction signal is higher than a first reference level which is the lowest level. In FIG. 6, the microcomputer 18 includes:
The judgment result latched by the latch circuit 26 is read out (S
T21), it is determined whether or not the level setting signal supplied to the level determining circuit 17 is the first level setting signal (ST22). Now, since the first level setting signal is being output from the microcomputer 18, the microcomputer 18 determines whether or not the reproduction signal is in the level over state based on the determination result obtained in step ST21. (ST23). Here, the level over state refers to a state where the level of the reproduction signal is higher than the reference level. If the reproduction signal is in the level over state, the microcomputer 18 further determines whether the level under state has already been detected (ST24).
Here, the level under state refers to a state in which the level of the reproduced signal is lower than the reference level. If the level under state has not been detected yet, the timer (t) used in the level under detection process ST50 described later is reset (ST25). And the microcomputer 18
Switches the first level setting signal to the second level setting signal (ST26). As a result, thereafter, the level determination circuit 17 determines whether or not the level of the reproduction signal is higher than a second reference level (for example, -65 dB) higher than the first reference level.

The microcomputer 18 executes step ST
After reading the determination result from the latch circuit 26 in 21, the process proceeds to step S27 shown in FIG. 7 via step ST22. In a state where the microcomputer 18 outputs the second level setting signal, it is determined whether or not the reproduction signal is in a level over state (ST2).
8). If the reproduction signal is in the level over state, it is further determined whether or not the level under state has already been detected (ST29). If the level under condition has not been detected yet, the timer (t) is reset (S
At T30, the microcomputer 18 switches the second level setting signal to a third level setting signal (ST3).
1). As a result, thereafter, the level determination circuit 17 determines whether or not the level of the reproduction signal is higher than a third reference level (for example, −60 dB) which is higher than the second reference level.

The microcomputer 18 executes step ST
After reading out the determination result from the latch circuit 26 in FIG.
The process proceeds to step ST32 shown in FIG. While the microcomputer 18 is outputting the third level setting signal, steps ST33 to ST35 are executed in the same manner as steps ST28 to ST30 when the microcomputer 18 outputs the second level setting signal. in this case,
If the reproduction signal is in the level over state and the level under state has not been detected yet, the microcomputer 18 switches the third level setting signal to the fourth level setting signal (ST36). As a result, thereafter, the level determination circuit 17 outputs the fourth reference level (for example,-
55 dB).

The microcomputer 18 executes step ST
After reading the determination result from the latch circuit 26 at 21, the process proceeds to step ST37 shown in FIG. 8 via steps ST22, ST27, and ST32. Step ST33 when the microcomputer 18 is outputting the third level setting signal while the microcomputer 18 is outputting the fourth reference level setting signal
Steps ST38 to ST40 are executed in the same manner as in steps ST38 to ST35. Thereafter, the microcomputer 18 reads the determination result from the latch circuit 26, and the step ST41 and the steps ST38 to ST40 are repeated.

As described above, the reference level set in the level determination circuit 17 sequentially increases from the first reference level to the fourth reference level. In this process, when it is determined that the reproduction signal is not in the level over state, the level under detection processing in step ST50 is executed. Background signal (noise) reproduced from the magnetic tape 13
Is extremely low, it is determined that the reproduction signal is not in the level over state in a state where the first reference level (the lowest level: for example, -70 dB) is set in the level determination circuit 17 (ST23). When the background signal (noise) is high, the fourth reference level (highest level:
For example, in the state where -55 dB) is set in the level determination circuit 17, it is determined that the reproduction signal is not in the level over state (ST38). If the background signal (noise) is moderate, it is determined that the reproduction signal is not in the level over state in the state where the second or third reference level is set in the level determination circuit 17 (ST28 or ST28). ST
33).

For example, when it is determined that the reproduction signal is not in the level over state in a state where the first reference level is set in the level determination circuit 17, the process proceeds from step ST23 to step ST51. That is, it is determined whether the level under state has already been detected (ST51). If the level under state has not been detected yet, the timer (t) starts (ST52).
Thereafter, a step ST53 of reading the judgment result latched by the latch circuit 26, a step ST54 of judging whether or not the reproduction signal is in a level over state based on the judgment result, and a timer (t) for a predetermined reference time t ₀ above or becomes whether the determining step ST55 is repeated. The reference time t ₀ is set to, for example, one second. If it is determined that the reproduction signal is in the level over state, the process returns to step ST24. Further, the timer (t) exceeds the reference time t _0, the microcomputer 18 detects the level under the state of the reproduced signal (ST56). Here, information indicating that the level under state has already been detected is stored in the internal memory of the microcomputer 18.

[0037] As described above, at the level under the detection process in step ST50, the reproduction signal is maintained lower than the reference level level reference time t ₀ or more times,
An under-level condition is detected.

Thereafter, the processing is performed in steps ST21 and S21.
The process proceeds to step ST23 via T22. If it is determined that the reproduction signal is not in the level over state, it is further determined whether or not the level under state has already been detected (ST51). At this point, since information indicating that the level under state has been detected is stored in the internal memory, the microcomputer 18 recognizes that the level of the reproduction signal has not changed (ST57). Then, steps ST21, ST22, ST23, ST51
And SR57 are repeated. When the reproduction signal rises (for example, music starts), it is detected in step ST23 that the reproduction signal is in an over-level state. If it is confirmed by referring to the information stored in the internal memory that the level under state has already been detected, the process proceeds to step ST60 shown in FIG. That is, the microcomputer 18 detects the rise of the reproduction signal.

The above processing for detecting the rise of the signal can be applied to the recording circuit of the magnetic recording / reproducing apparatus 11. FIG. 9 shows a recording circuit. 9, the same components as those in FIG. 1 are denoted by the same reference numerals.

In FIG. 9, an input unit 24 receives an audio signal supplied from an external unit, and the audio signal is supplied from the input unit 24 to the analog / digital converter 20. The audio signal output from the analog-to-digital converter 25 is supplied to the memory 22 and written into the memory 22. The audio signal read from the memory 22 is supplied to a recording signal output circuit 16c of the signal processing circuit 16. The recording signal output circuit 16c performs a process of adding an error correction code to the audio signal, an interleaving process, a modulation process, and the like, and generates a recording signal to be recorded on the magnetic tape 13 (DAT). The sub-code processing circuit 16b of the signal processing circuit 16
Address information and various subcodes are added to the recording signal. The recording signal output from the signal processing circuit 16 is recorded on the magnetic tape 13 via the rotary head 15.

The reading process and the writing process of the memory 22 are controlled by the memory controller 19 in accordance with an instruction from the microcomputer 18. The microcomputer 18 includes a signal processing circuit 16 and a driving mechanism 12.
Also control.

The audio signal is supplied from the analog / digital converter 25 to the level determination circuit 17. The level determination circuit 17 is configured as shown in FIG. The microcomputer 18 detects the rising edge of the audio signal based on the determination result obtained by the level determination circuit 17. When the microcomputer 18 detects the rising edge of the audio signal, the address corresponding to the rising position of the audio signal is stored in the microcomputer 1.
8 is stored in the internal memory. When a recording signal corresponding to the audio signal input to the recording circuit is recorded on the magnetic tape 13, an address indicating the rising position of the audio signal is supplied from the microcomputer 18 to the subcode processing circuit 16b. Subcode processing circuit 16
b supplies the start ID to the rotary head 15 so that the start ID is recorded at a position corresponding to the address indicating the rising position of the audio signal.

The microcomputer 18 executes processing for detecting the rising edge of the audio signal in accordance with the flowcharts shown in FIGS. 10, 11, 12, and 13.

The microcomputer 18 first supplies a fourth level setting signal to the level determination circuit 17, and the level determination circuit 17 outputs the fourth reference level (for example, -55 dB), which is the highest level of the audio signal. ) Is determined. Thereafter, the processing shown in FIGS. 10 to 13 is started.

In FIG. 10, the microcomputer 1
8 reads the determination result latched by the latch circuit 26 (ST101), and determines whether the level setting signal supplied to the level determination circuit 17 is the fourth level setting signal (ST102). Since the microcomputer 18 has output the fourth level setting signal, the microcomputer 18 determines whether or not the audio signal is in a level over state based on the determination result obtained in step ST101. While the audio signal is valid, a level over state where the level of the audio signal is higher than the fourth reference level (for example, -55 dB) is maintained. Therefore, after this, steps ST101, S101
T102, ST103, ST108 and ST111 are repeated.

When the audio signal falls and its level is, for example, a first reference level (for example, -70 dB)
When the value becomes between the second reference level and the second reference level (for example, -65 dB), the processing is performed as follows.

The microcomputer 18 determines in step S
In T103, it is determined that the audio signal is not over the level, and it is determined in step ST104 whether the fall of the audio signal has already been detected. If the fall of the audio signal has not been detected yet, steps ST105, ST106 and ST107 are executed, the timer T is started, and the third level setting signal is sent to the microcomputer 18
Is supplied to the level determination circuit 17 from As a result, the level determination circuit 17 starts the determination process using the third reference level (for example, -60 dB). After the microcomputer 18 reads the determination result from the level determination circuit 17 in step ST101, the processing proceeds to step ST102 shown in FIG.
Go to 121.

In FIG. 11, the microcomputer 1
8 determines in step ST121 that the third reference level is set in the level determination circuit 17, and then determines in step ST122 whether the audio signal is in a level over state. In this case, since the level of the audio signal has reached a value between the first and second reference signal levels, the process proceeds from step ST122 to step ST123. In step ST123, it is determined whether or not the fall of the audio signal has already been detected. Since the fall of the audio signal has not been detected yet, the process proceeds to step ST12.
At 4, it is determined whether the previous reference level is greater than or equal to the third reference level. In this case, since the previous reference level is the fourth reference level higher than the third reference level,
In steps ST125 and ST126, the timer T is reset and restarted. Thereafter, the microcomputer 18 supplies a second level setting signal to the level determination circuit 17 in step ST127. As a result, the level determination circuit 17 starts a determination process using the second reference level (for example, -65 dB). After the microcomputer 18 reads the determination result from the level determination circuit 17 in step ST101, the processing is as follows:
The process proceeds to step 151 shown in FIG. 12 via steps ST102 and ST121.

In FIG. 12, the microcomputer 1
8 determines in step ST151 that the second reference level is set in the level determination circuit 17, and then steps ST152 to ST157 are executed in the same manner as steps ST122 to ST127 shown in FIG. As a result, the microcomputer 18 supplies the first level setting signal to the level determination circuit 17. Then, the level determination circuit 17 outputs the first reference level (for example, -70 dB).
Is used to perform the determination process. Microcomputer 18
After reading the determination result from the level determination circuit 17 in step ST101, the process proceeds to step ST10.
The process proceeds to step ST170 shown in FIG. 13 via ST122, ST122 and ST151.

In FIG. 13, the microcomputer 1
8 determines in step ST170 that the first reference level is set in the level determination circuit 17, and in step ST171, determines whether the audio signal is in a level over state. In this case, since the level of the audio signal has reached a value between the first and second reference levels, the process proceeds from step ST171 to step ST177. In step 177,
It is determined whether the fall of the audio signal has already been detected. At this point, since the falling edge of the audio signal has not been detected yet, step ST17
At 8, it is further determined, using the first reference level, whether an under-level condition of the audio signal has already been detected. Since such an under-level state has not yet been detected, furthermore, in step ST179, FIG.
Timer T restarted in step ST156 shown in FIG.
Is determined to have reached 3 seconds. If the timer T has not reached 3 seconds, the first reference level is switched to the second reference level in step ST18. Thereafter, the processing is performed from step ST181 to steps ST101 and ST101.
Step S102 shown in FIG.
It returns to T151. Then, steps ST151 and ST1
52, ST153, ST154 and ST157 are sequentially executed. As a result, the second reference level is switched to the first reference level. Thereafter, step S shown in FIG.
T170, ST171, ST177, ST178, ST
179 and ST181, and step ST1 shown in FIG.
51, ST152, ST153, ST154 and ST1
57 are performed alternately until the timer T reaches 3 seconds. That is, the level determination circuit 17 performs the determination process while alternately switching the first and second reference levels. If it is determined in step ST179 shown in FIG. 13 that the timer T has reached three seconds, the microcomputer 1
8 detects the falling edge of the audio signal in step ST180. Then, the first reference level is switched to the second reference level in step ST18. Thereafter, the process returns to step ST151 shown in FIG.

In FIG. 12, the microcomputer 1
If it is determined in step ST151 that the second reference level has been set in the level determination circuit 17, it is determined in step ST152 whether the audio signal is in a level over state. At this point, since the level of the audio signal is between the first and second reference levels, the processing is performed from step ST152 to step ST15.
Proceed to 3. If it is determined in step ST153 that the rising edge of the audio signal has already been detected, the second reference level is held as it is in step ST158. Thereafter, steps ST151, ST152,
ST153 and ST158 are repeated until the audio signal rises (until the music is started).
When the audio signal rises and the level of the audio signal exceeds the second reference level, step ST15
At 2, it is determined that the audio signal is in a level over state. At this point, since the falling edge of the audio signal has already been detected, the rising edge of the audio signal is detected based on the determination result obtained in step ST159.

As described above, at the end of the music, the audio signal is at the first reference level (eg, -70d).
If the level falls to a level between B) and a second reference level (for example, -65 dB), a rising edge of the audio signal (corresponding to the next music) is detected using the second reference level. If the audio signal drops to a level between the second reference level (eg, −65 dB) and the third reference level (eg, −60 dB) at the end of the music, the timer T reaches 3 seconds, Steps ST151, ST152, ST159, ST16 shown in FIG.
0, ST161 and ST163, and steps ST121, ST122, ST123, ST124 and ST127 shown in FIG. 11 are alternately performed. That is, the level determination circuit 17 performs the determination process while alternately switching between the second reference level and the third reference level. In this case, when the level of the audio signal exceeds the third reference level, a rising edge of the audio signal corresponding to the next music is detected. Further, if the audio signal drops to a level between the third reference level (for example, -60 dB) and the fourth reference level (for example, -55 dB) at the end of the music, the timer T is set to 3 seconds. Figure 1
Steps ST121, ST122, ST12 shown in FIG.
9, ST130, ST131 and ST133, and FIG.
Steps ST101, ST102, ST103,
ST104, ST105 and ST107 are performed alternately. That is, the level determination circuit 17 performs the determination process while alternately switching between the third reference level and the fourth reference level. In this case, when the level of the audio signal exceeds the fourth reference level, a rising edge of the audio signal corresponding to the next music is detected.

When the audio signal drops below a first reference level (eg, -70 dB),
After the timer T is restarted in step ST156 shown in FIG. 2, steps ST170, ST171, and ST17 are performed so as to monitor whether the timer T reaches 3 seconds.
2, ST174 and ST176 are repeated.
When the timer T reaches 3 seconds, in step ST175,
The fall of the audio signal is detected. in this case,
The level of the audio signal is the first reference level (for example,
(−70 dB), the rising of the audio signal corresponding to the next music is detected (ST171 and ST171).
177).

When the audio signal fluctuates in the low level range between the first reference signal and the fourth reference signal, the timer T is repeatedly reset (step S shown in FIG. 11).
T130, ST134, ST135 and ST136, steps ST160, ST164, STY1 shown in FIG.
65 and ST166 and step ST17 shown in FIG.
8, ST182, ST183 and ST184). Therefore, in this state, the rise of the audio signal is not detected.

[0055]

As described above, according to the present invention,
A position in the memory corresponding to a rising edge of the reproduction signal to be stored in the memory is detected, and reading of the reproduction signal from the memory is started from the detected position. Therefore, D
Even in the case of a tape-shaped recording medium such as an AT, signal reproduction can be performed immediately from its rise.

[0056]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a magnetic recording / reproducing device (DAT).

FIG. 2 is a block diagram showing a level determination circuit provided in the magnetic recording / reproducing apparatus shown in FIG.

FIG. 3 is a flowchart illustrating a process of reproducing an audio signal from a DAT.

FIG. 4 is a diagram showing an operation in a ring buffer according to the processing shown in FIG. 3;

FIG. 5 is a diagram showing an operation according to the processing shown in FIG. 3;

FIG. 6 is a flowchart showing a process for detecting a rising edge of a reproduction signal.

FIG. 7 is a flowchart illustrating a process for detecting a rising edge of a reproduction signal.

FIG. 8 is a flowchart showing a process for detecting a rising edge of a reproduction signal.

FIG. 9 is a block diagram illustrating a recording apparatus including a unit that detects falling and rising edges of a signal.

FIG. 10 is a flowchart showing a process for detecting a fall and a rise of an audio signal to be recorded in a DAT.

FIG. 11 is a flowchart showing a process for detecting a fall and a rise of an audio signal to be recorded in a DAT.

FIG. 12 is a flowchart showing a process for detecting a fall and a rise of an audio signal to be recorded in DAT.

FIG. 13 is a flowchart showing a process for detecting a fall and a rise of an audio signal to be recorded in a DAT.

FIG. 14 is a diagram showing recording tracks of a CD (compact disc).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Magnetic recording / reproducing apparatus 12 Drive mechanism 13 Magnetic tape 16 Signal processing circuit 17 Level judgment circuit 18 Microcomputer 19 Memory controller 20 D / A converter 22 Memory 23 Operation key

Claims (4)

(57) [Claims] 1. A signal reproducing apparatus for reproducing an audio signal recorded on a recording medium using start position information indicating a start position of the audio signal on the recording medium. A reproduction signal output unit for outputting the reproduction signal; a memory unit for storing the reproduction signal; and a memory for storing the reproduction signal output from the reproduction signal output unit in a predetermined range on a recording medium including a position specified by the start position information. Control means for storing the rising edge of the reproduction signal stored in the memory means by the control means, a rising position detecting means for detecting a position in the memory means of a rising edge of the reproduction signal, and a position detected by the rising position detecting means. A memory control unit for starting reading of a reproduction signal from the memory unit. 2. The signal reproducing apparatus according to claim 1, wherein the rising position detecting means compares the level of the reproduction signal with a reference level, and the reproduction signal based on a comparison result by the comparison means. And a detecting means for detecting that the level of the reproduced signal has transitioned from a state lower than the reference level to a state higher than the reference level to detect a rising position of the reproduced signal. 3. The signal reproducing apparatus according to claim 2, wherein said rising position detecting means further comprises a reference level changing means for changing said reference level according to the level of the reproduced signal. 4. A signal reproducing apparatus according to claim 3, wherein the reference level changing means selectively sets one reference level from a plurality of reference levels, and sets the level of the reproduction signal to the reference level. Level determining means for determining whether the level is lower than the reference level set by the means, and setting by the reference level setting means when the level determining means determines that the level of the reproduction signal is not lower than the reference level. And a change control unit for changing the set reference level.